Wireless telephony



7 1,629,685 y 1927' r w. 'r. DITCHAM WIRELESS TELEPHONY Filed D90. 18. 1920 (14w WW l 'atented -May 24, 1927.

UNITED STATES PATENT OFFICE.

CORPORATION OF AMERICA, OF NEW YORK, N. Y., A

CORPORATION OF DELAWARE.

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Application filed December 18, 1920, Serial No. 481,584, and in This invention relates to improvements in wireless telephony, and its object is to provide a transmitter in which small changes of condition set up by the voice in one part i of the system will produce in another part much greater changes which may be utilized to transmit the speech in an efiective manner,

According to this invention means are provided whereby the waves of speech may vary the frequency of the oscillations in one of two primary oscillatory circuits which with continuous oscillations preferably from thermionic generators, and means are provided for rectifying the oscillations in a secondary oscillation circuit tuned to a freuency equal to the difference between the equencies of the primar circuits and so 2 arranged that the beat requency oscillations resulting from the rectification induce currents in the secondary circuit which may be coupled either directly or through an amplifier to an aerial, or to the grid of a 2 thermionic valve controlling the radiation from a continuous wave transmitter.

Since the beat frequency is less than either of the'primaryfrequencies a variation in one of the primary frequencies results in a greater proportional variation in the beat frequency.

The variation in frequency may be caused in the case of valve oscillators by imposing a voice produced voltage variation on the grid of the oscillating valve in a known manner, or acondenser forming part of the valve oscillating circuit and capable of being varied in capacity by the s eh waves may be employed,- or any ot er suitable method may be used.

In some cases the speech may be caused to vary the frequencies of both the primary circuits in' opposite se Y The secondary circuit may be tuned to a frequency equal to the difference of the freuencies of the rimary circuits or to a s 'ghtly different uency preferably such that the maximum variation possible in the rimary frequencies in one with this frequency.

are tuned to different frequencies and fedsense will pro-' uce abeat which just reaches resonance Great Britain February 28, 1920.

i The accompanying drawing .shows by way of example diagrams of the invention employed as a wireless telephone transmitter in Figure 1 and as a subcontrol modulal tor in a wireless telephone transmitter in Fi re 2, I i

A A A, A, and B, B, B, B, represent valves and circuits generating osclllations of frequency a, M, n, n.

- C and 0 represent rectifiers in connection with circuits 1) and l) tuned to a frequency of n -n and *nP-n respectively.

E and F F F, represent a circuit and valves magnifying the frequency 19-4? and G is an aerial circuit tuned to a frequency H and H are absorbing valves for modulating the oscillations in J in the grid circuit of which is a circuit I tuned or nearly tuned to the frequency 119-10.

K is the source of high frequency exciting J.

M is a microphone by which the frequency 12- or 'n can be modulated.

Having now particularl described the nature of my invention an in what manner the same. is to be performed I declare that. what I claim is 1. In a wireless telephone transmitter, the combination of two primary oscillatory cir-. cuits tuned to different frequencies, means for supplying continuous oscillations thereto, means whereby speech waves can vary the frequency of the oscillations in one of the circuits, and an oscillatory rectiflying circuit tuned to a frequency substantia ly' equal to the difference between the frequencies of the primary circuits and coupled to an aerial.

2. In a wireless telephone transmitter, the combination of two primary oscillatory circuits tuned to different frequencies, means for supplying continuous oscillations thereto, means whereby speech waves can vary the frequency of the oscillations in one of the. circuits, and an oscillatory recti ing circuit tuned to a frequency substantia y equal to the difference between. the frequencies of the primary circuits and coupled to-an aerial- .through an amplifier.

WILLIAM THEODORE DITCHAM. 

